On Thu, May 17, 2012 at 09:30:42AM -0700, David Daney wrote: > Date: Thu, 17 May 2012 09:30:42 -0700 > From: David Daney <ddaney.cavm@xxxxxxxxx> > To: Yong Zhang <yong.zhang0@xxxxxxxxx>, ralf@xxxxxxxxxxxxxx > CC: linux-rt-users@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, > david.daney@xxxxxxxxxx, tglx@xxxxxxxxxxxxx > Subject: Re: [PATCH -rt] MIPS: Octeon: convert smp_reserve_lock to raw > spinlock > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 05/17/2012 03:15 AM, Yong Zhang wrote: > >From: Yong Zhang<yong.zhang@xxxxxxxxxxxxx> > > > >Because __cpu_disable is called in atomic context and spinlock > >is a mutex on -rt. > > > >Signed-off-by: Yong Zhang<yong.zhang0@xxxxxxxxx> > >--- > > arch/mips/cavium-octeon/smp.c | 6 +++--- > > 1 files changed, 3 insertions(+), 3 deletions(-) > > > >diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c > >index ef9c34a..473c72b 100644 > >--- a/arch/mips/cavium-octeon/smp.c > >+++ b/arch/mips/cavium-octeon/smp.c > >@@ -257,7 +257,7 @@ DEFINE_PER_CPU(int, cpu_state); > > > > extern void fixup_irqs(void); > > > >-static DEFINE_SPINLOCK(smp_reserve_lock); > >+static DEFINE_RAW_SPINLOCK(smp_reserve_lock); > > > > Ralf added this in 773cb77d (MIPS: Cavium: Add CPU hotplugging code.) > > I'm not even sure what this lock is supposed to be protecting, so I > would like Ralf to take a look. > > You can add an Acked-by: from me for either this patch as is, or if > Ralf thinks it is OK, removing the lock entirely. > > In any event we can merge this via Ralf's tree. The 773cb77d patch has a long history but I think I first worked on it for Wind River Linux 2.0 which was 2.6.21-based, then broke it out and pushed it upstream. In 2.6.21 it was probably infected by the the smp_reserve_lock virus in the s390 code for no good reason. So I agree, the lock can be dropped and I'm queueing a patch to do so for 3.5. Ralf -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
